Engine fan

ABSTRACT

In a fan module ( 10 ) of a vehicle engine, the fixed shroud ( 12 ) of the module ( 10 ) has a circular opening ( 16 ) receiving a fan ( 14 ) rotating about a main axis (X). The opening ( 16 ) is circumvented by a peripheral wall ( 18 ) cylindrically extending in the downstream direction (DD) beyond the fan ( 14 ) toward a corner edge where the wall ( 18 ) angles radially and inwardly to extend toward a circular downstream edge. The downstream portion of the peripheral wall ( 18 ) forms an annular channel (C) opening in the upstream direction (UD) The channel (C) forming an axial continuation of the gap (G) that is between the tips ( 22 ) of the blades ( 20 ) of the fan ( 14 ). The gap (G) is continuous, non-divided and non-partitioned.

TECHNICAL FIELD

The present invention relates to a fan module for cooling a vehicle engine. In particular the invention relates to the structure of the shroud.

BACKGROUND OF THE INVENTION

Engine fan modules are arranged in the front of a vehicle to generate an air stream that passes through heat exchangers cooling the engine's components. A peripheral back stream flows in the opposite direction as the main stream and passes in the gap between the tip of the blades of the fan and the surface of the opening shroud. To reduce such back flow features have been developed in the structure of the shroud.

U.S. Pat. No. 7,478,993 discloses a downstream profile of the shroud supposed to provide a Coanda effect. U.S. Pat. No. 5,489,186 discloses another downstream profile wherein flat surfaces, integral to the shroud, are arranged in the gap so that the structure is reinforced and, the back stream air flow is axially directed and cannot rotate within the gap. Other fan modules are known from US2003161728, DE4414893 and WO9506822.

Developments are required to further improve the efficiency of the fan module.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a fan module of a vehicle engine. The module comprises a fixed shroud that receives in an opening a fan rotating about a main axis. The opening may be circular. The opening is circumvented by a peripheral wall extending in the downstream direction, relative to the main air flow, beyond the fan toward a corner edge where the wall reorients radially and inwardly to extend toward a circular downstream edge. The reorientation of the peripheral wall may be done smoothly, for instance in a curve, or abruptly with an angle. The downstream portion of the peripheral wall forms an annular channel opening in the upstream direction. The channel forms an axial continuation of a continuous space to the gap that is between the tips of the blades of the fan and the peripheral wall. The gap is continuous, non-divided and non-partitioned.

In an embodiment, the channel is also free of obstacles forming a continuous, non-divided and non-partitioned annular space.

It may happen that due to structural parts for instance, the channel may be interrupted.

In another embodiment, reinforcement ribs may be formed and confined in the channel. The ribs do not form in the gap. Furthermore, a 360° aperture is formed between downstream outer edge of the fan and the downstream edge of the peripheral wall so that the annular channel is downstream said 360° aperture and, in operation of the module a peripheral counter air stream is able to enter the gap and the channel through said 360° aperture.

The diameters of the downstream outer edge of the fan and of the downstream edge of the peripheral wall may be equal so that the circular edge faces the very tips of the blades. In another embodiment, the diameter of the circular edge is smaller than the outer diameter of the fan. In yet another embodiment, the diameter of the circular edge is larger than the outer diameter of the fan.

More specifically, the peripheral wall extending from the corner edge to the circular edge may form a quadrant, or a quarter of circle.

In another embodiment, the peripheral wall extending from the corner edge to the circular edge is frustoconical with apex upstream the fan.

The fan may be provided with an outer cylindrical ring joining the tips of the blades. In this case, the gap is the space between said ring and the peripheral wall. The portion of the ring that joins the tips of the blades may be cylindrical or may have another profile such as a conical or curved shape.

Furthermore the shroud is provided with at least one stator-arm radially extending and integrally connecting the peripheral wall between the corner edge and the circular edge externally of the annular channel.

The peripheral wall may be cylindrical or comprise a cylindrical portion, especially the portion facing the tips of the blades or, may have another profile such as a conical or curved shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying figures.

FIG. 1 is a section of a fan module.

FIGS. 2 and 3 are detailed views in section of a fan and shroud presenting details of different embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As well-known and represented in FIG. 1, a fan module 10 comprises a fixed shroud 12 and a revolving fan 14, the fan and shroud being generally molded in plastic. The shroud 12 is of a general rectangular shape and has a large circular opening 16 delimited by a peripheral wall 18. The fan 14 is received in the opening 16, driven in rotation about a main axis X by an electric motor M. The fan 14 comprises blades 20 which tips 22 are close to the peripheral wall 18. Furthermore, the tips 22 of the blades 20 are integrally connected by a circular ring 24 but, in alternative embodiments, this latter feature is not present. To avoid any interference, an annular gap G is accommodated between the ring 24, or the very tip 22 of the blades 20, and the peripheral wall 18 of the opening 16.

In operation, the fan 14 generates a main air stream F1 flowing in the downstream direction DD, from upstream the fan 14, on the left of FIG. 1, to downstream the fan 14, on the right on FIG. 1 and, a counter air stream F2 flows inside the annular gap G in the opposite upstream direction UD.

To better control said counter air stream F2 and optimize the aerodynamic efficiency and acoustic performance of the fan module 10, a first embodiment is now described in reference to FIG. 2.

The fan 14 is provided with a circular ring 24 joining the tips 22 of its blades 20. As can be seen on the figure, the ring 24 has a central cylindrical section 26 covering the blades 20 and an upstream section 28 extending outwardly in a disc portion perpendicularly to the central section 26. Other profiles are possible such as a cylindrical profile only.

The peripheral wall 18 of the opening 16 extends from an upstream edge 32, on the left of the figure, to a downstream edge 34, on the right of the figure. Between said edges 32, 34, the peripheral wall 18 extends in an upstream portion 36, comprising a series of faces forming steps so to follow the profile of the ring 24. Said upstream portion 36 continues in a central portion 38 that is cylindrical and that axially X extends downstream the fan 14 until a corner edge 40. Finally, after the corner edge 40, the peripheral wall 18 angles abruptly extending radially inwardly into a downstream portion 42 until the downstream edge 34. As can be observed on the embodiment represented on the figure, the section in the axial plan of the figure of the downstream portion 42, at the corner edge 40 the wall 18 abruptly angles radially and inwardly to extend toward a circular downstream edge 34. The downstream portion 42 forms a quadrant 44 with radius R substantially equal to the width of the gap G, the center of said quadrant 44 being located upstream the corner 34. The circular portion formed by the quadrant 44 is followed by a short straight portion so that, the downstream edge 34 faces the downstream edge of the ring or of the blade, and forms into the gap G a 360° opening 48 of width W.

As can be observed on the figure, the downstream portion 42 defines a circular channel C open in the upstream direction UD. The channel C is in continuity to the gap G, and is positioned downstream the 360° opening 48 while the main part of gap G is upstream the 360° opening 48.

Other geometries than a quadrant may be chosen for channel C, geometries that would not require an abrupt angle of the wall 18 at the corner edge 40. The abrupt reorientation done by the peripheral wall and forming the corner edge 40, can, in other embodiments, be much smoother that as represented on the figures. For instance, the peripheral wall could form a continuous semi-circular U-turn.

Multiple further geometrical alternatives can be derived from this first embodiment. For instance, as detailed above, the tips 22 of the blades 20 may be free without connecting ring. Also, the quadrant 44 may not follow an exact quarter of circle and, may not be followed by a short straight portion.

As can also be observed on the figure, the shroud 12 comprises radially extending arms 50, usually identified as stators 50 and which are integrally formed joining the outer face of the quadrant 44. These arms are integral to the shroud and can be single-molded in plastic material. Importantly enough to be underlined in this description, in the present embodiment the gap G and the channel C extend all around the fan 14 in a continuous space non-divided or non-interrupted or non-partitioned by, for instance reinforcement ribs or other partitioning walls.

In certain non-represented specific embodiments, it may happen that the channel is interrupted on an angular portion, this to enable packaging with other structural part.

In operation, the air passes through the fan 14 then a minor peripheral portion forms the counter air stream F2 that enters through the opening 48 into the gap G and channel C. Therein the stream F2 flows and revolves into the gap G and channel C prior to exiting upstream.

A second embodiment is now described by way of differences to the first embodiment and in reference to FIG. 3.

In the second embodiment, the downstream portion 42 forms a frustoconical portion with apex on the main axis X upstream the fan 14. The diameter of downstream edge 34 is smaller than the diameter of the ring 24 so the very tips 22 of the blades 20 face the inside of the gap G.

In a non-represented alternative the diameter of downstream edge 34 is larger than the diameter of the ring 24 so the downstream edge 34 faces the inside of the channel C.

Furthermore, as can be observed in this second embodiment, small

reinforcement ribs 52 are integrally formed and confined inside the channel C, joining the downstream portion 42 to the central portion 38. The portion of the gap G that is upstream the 360° opening 48 remains a continuous space non-divided or interrupted or non-partitioned by the ribs 52.

While the above description constitutes the preferred embodiments of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.

In the present description, the following references have been utilized:

10 fan assembly

12 fixed shroud

14 revolving fan

16 opening

18 peripheral wall

20 blades

22 tips of the blades

24 ring connecting the blades

26 cylindrical portion

28 disc portion

30 downstream edge of ring or of the blade

32 upstream edge of the peripheral surface

34 downstream edge

36 upstream portion

38 central portion

40 corner edge

42 downstream portion

44 quadrant portion

46 frustoconical portion

48 360°-opening in the gap

50 stator

52 reinforcement ribs

X main axis

F1 main air stream

F2 counter air stream

G annular gap

C channel

UD upstream direction

DD downstream direction radius of the quadrant width of the 360° opening electric motor 

1. A fan module (10) of a vehicle engine, the fan module having an upstream direction (UD) and a downstream direction (DD) axially opposite to the upstream direction, the fan module comprising a fixed shroud (12) receiving, in an opening, (16) a fan (14) with blades (20) rotating about a main axis (X), the opening (16) being circumvented by a peripheral wall (18) extending in the direction (DD) beyond the fan (14) toward a corner edge (40) where the peripheral said wall (18) reorients radially and inwardly to extend toward a circular edge (34) downstream of the fan (14) so that a downstream portion (42) of the peripheral wall (18) forms an annular channel (C) opening in the upstream direction (UD), the channel (C) forming a continuous space to the gap (G) that is between tips (22) of the blades (20) of the fan (14) and the peripheral wall (18), the gap (G) being continuous, non-divided and non-partitioned, wherein a 360° aperture (48) is formed between a downstream outer edge (30) of the fan (14) and the circular edge (34) of the peripheral wall (18), wherein the annular channel (C) is arranged downstream of the 360° aperture (48) and, during operation of the module (10), a peripheral counter air stream (F2) is able to enter the gap (G) and the channel (C) through the 360° aperture (48).
 2. The fan module (10) according to claim 1, wherein the channel (C) is also free of obstacles and forms a continuous, non-divided and non-partitioned space.
 3. The fan module (10) according to claim 1, wherein reinforcement ribs (52) are formed and confined in the channel (C).
 4. The fan module (10) according to claim 1, wherein the circular edge (34) and the downstream outer edge (30) of the fan (14) have equal diameters so that the circular edge (34) faces the tips (22) of the blades (20).
 5. The fan module (10) according to claim 1, wherein the circular edge (34) has a smaller diameter than the downstream outer edge (30) of the fan (14).
 6. The fan module (10) according to claim 1, wherein the circular edge (34) has a larger diameter than the diameter of the downstream outer edge (30) of the fan (14).
 7. The fan module (10) according to claim 4, wherein the downstream portion of the peripheral wall (18) extends from the corner edge (40) to the circular edge (34) and has a profile forming a quadrant (44).
 8. The fan module (10) according to claim 4, wherein the downstream portion of the peripheral wall (18) extends from the corner edge (40) to the circular edge (34) and forms a frustoconical portion (46) with an apex upstream of the fan (14).
 9. The fan module (10) according to claim 1, wherein the fan (14) comprises a ring (24) with a portion (26) joining the tips (22) of the blades (20), the gap (G) being between the ring (24) and the peripheral wall (18).
 10. The fan module (10) according to claim 8, wherein the portion (26) of the ring (28) that joins the tips (22) of the blades (20) is cylindrical about the main axis (X).
 11. The fan module (10) according to claim 9, wherein the portion (26) of the ring (24) that joins the tips (22) of the blades (20) is non-cylindrical, the portion being for instance conical or curved.
 12. The fan module (10) according to claim 1, wherein the shroud (12) is provided with at least one stator-arm (50) radially extending and integrally connecting the peripheral wall (18) between the corner edge (40) and the circular edge (34) externally of the annular channel (C).
 13. The fan module (10) according to claim 1, wherein the peripheral wall (18) is cylindrical.
 14. The fan module (10) according to claim 1, wherein the peripheral wall (18) is non-cylindrical.
 15. The fan module (10) according to claim 14, wherein the peripheral wall (18) is conical.
 16. The fan module (10) according to claim 14, wherein the peripheral wall (18) is curved. 